By way of example, the turbomachine is a turbocompressor or a hydroturbine. In a turbomachine, energy is transmitted by a flowing fluid (gas or liquid). The energy transmission is carried out in this case by way of a rotor with rotary shaft. Rotor blades, wings or blades, which are formed in such a way that a pressure difference (Δp) emerges in the fluid flow (volumetric flow) between the front side and rear side of the rotor, are arranged at the rotary shaft (driveshaft or output shaft).
The power and power intake or power output of the turbomachine (or of individual turbomachine stages) are established over a plurality of measured process parameters (operating parameters). Here, problems are caused by the measurement accuracy of employed instruments for measuring the process parameters and the frequent lack of knowledge about a gas composition or the lack of knowledge about further operating parameters. Often, the measurement has to be carried out at a constant load over a relatively long period of time in this case. What results from this is that the turbomachine can very often not be driven in the ideal efficiency range.